Telephone receiver



K sept, 29, '1925. 1,555,033

A. B. SMITH TELEPHONE RECEIVER 4Filed Aug. l, 1921 Patented sept. 29, 1925.

duplication'nlednugutn1921! seiialnausgooef Y TaaZZwhom/zt may] cof/wem( f1 *L i f :Be it known that IgARTHUR Besser SMITH, a citizen Aofthe United- States of America, and` a residentof'Evanston, Cook County, 5 and State ofIllinoisfhave'invented certain new i and useful Improvements `in Telephone Receivers, of which the following is a specifi cation. r f V' The present invention'relates'in general to telephone receiverslandjhas for its principalv l ob'jectthelprovisionfofa new and improved telephone receiver ofthe. permanent magnet type. in'wh-ich isi embodied a new feature or principle of construction which substantially increases..theleiciencyuof the receiver.

. AIn the accompanying drawings,"Fig. 1 .is a side viewoa telephone receiver i embodying theinventi'on, with theshell out lawayto show the variouspartsy- Fig.w2 is anend view ofthe sameuwith the receiver cap, dia-` phragnn-'jand the coil winding removed. Fig.v1 3? is a side view of the y-lower endof the receiver without the shell and having aportion of the cup` cut awayfso'astoshow the internal construction. Fig. 4 is a view of one of the receiver pole' pieces showing the cor'e ofthe magnet coil, while Fig. V5 is a viewofftheotherpole piecefu f n i As illustrated-n the drawings, it will be 30 seen that the improved receiver comprises the usual hard rubber shell 1, cap 2, cup 4, diaphragm 12, and permanent magnet 20. To the permanent horseshoe magnet are fastened, by means of the screw 11, the soft iron pole pieces 8 and 9. There is clamped between these pole pieces the end of the nonmagnetic cup 5, the end of the latter being recessed sliohtly in order to maintain the pole pieces in their proper position. In ad` dition to this, the projections 21 and 22, and 23 and 24 on the two pole pieces have corresponding holes in the adjacent portion of the cup and can thus be firmly clamped in position. A detailed view of one of these pole pieces is shown in Fig. 4 and from this figure it will be noted that the pole piece 9 is bent to form a right angle and on this bent portion there is riveted the pin 15. Upon this pin there is wound the coil 10 `of the electromagnet. A detailed view of the other pole piece is `shown in Fig. 5 and from this it will be seen that the pole Vpiece 8 is so formed that when the receiver is assembled the two lugs on this pole piece will come on the outside of the coil which is i wound I:on thev `extended portion of` the` piece 9; This isfs'hown clearlyin Figs. 2 and 3.y Thereisbafsmallairgapfbetweerr the- -two pole pieces beneath the coil 'when assembled which greatly increases the `ieiiicie'n'cyf off the l receiver, as will be explained ffully. hereinafter. Oni either :sideof the pole piece` 8 there are located the 'terminals 7 "and `16y to rwhich are attachedl the wires leading tot the:electromagnet.'` `,It willlbeseen that the coilf 10 ofthe electromagnet is `located right at# the c enter othecup where' it will have' the. greatest effect on thediaphragm 12.l 'sf Itlgaving described themechanical construction or' theimproved receiver its theory of operation will now be gone into. *ThemagneticA circuit off the 'permanent v magnet includesffthe pole`piece"9,-` pin'l, the1diaf phragin 12, and f-both sides of the pole piecei 8.15.5141l certainfia'mount of leakage iu'x of course will follow the gap betweenip'ole' pieces below the 'coi-l1" without passing through the` diaphragm 12,1 due to 'the fact that the bent over'endi of= pole-'piece9 is close tothe polepiecegS. The effectsof the varying magnetic liux produced by the voice cur-A` rentsdn the coil` o f the lelectroniagne't` vare localizedinvthe pole pieces, that is, thelux4 generated by the coil ris set up inthe following circuit: The bent portion of the pole piece 9, pin 15, diaphragm 12, lugs of the pole piece 8, and the gap between the pole pieces. It will be noted that there is but a very short length of iron included in the magnetic circuit which is subject to rapid change of magnetism at conversational frequencies, being merely the two lugs on the pole piece 8 and the pin and angle upon which it rests on the pole piece 9. This magnetic circuit is made up of soft iron having high permeability and does not include, as was the case in the prior receivers of this type, the permanent magnet which` is made of hard steel having a relatively low permeability. In the present case there is a leakage path of low reluctance provided by a small gap between the pole pieces so that the magnetism generated by the coil has only to affect the small amount of soft iron in the magnetic circuit including the pole pieces; that is, the current variation in the coil produces a relatively greater change in the attractive force upon the diaphragm than has been formerly the case in the prior receivers of this type. Looking at this from another angletheeffeet o the conversational alternating currentsl is snehl the@ whenrk the current is iowing in the coil in sucha direction as` to assist themmagnetism deg-KAn 6 velbpediby fthe "y permanent l y' lessL of g the magnetic= llxzis sliuntd byt'hcaii that is, there is less leakage flux. However,

when the current iows in the coil. O "insncli a direction that the magnetism@ setgvnp bygit opposes the magnetism setup by the permainagnet nf-11emee lHugin in shuntedf by: the; air, gakhietwn? thefplefpieces; :that issy; there:

.Slufte Of-s thissreceverwherein:- piees; of softfiion constitute the? main# ofA the g magnetic circuit which. is sub te? the eapid vari-ation. foff ,magnetisme pigodiedg-hy Ieur-r-ents a-t eniyrversationalfm frestruction pnoducea most veigiiiegnt\.1%eceve12.` @ther advantages-lie inf-51th@ alflain-.gementv whenebgsj` a 'single coil-- ,eszeegrt'a` y.aan attractive forceg upon the 'center of the.: diaphragm and! inst-lia oensmuetionvofw the; ipole 9? pieces-,sei ,that there-:is .unfiffermpull on the".

16;,1 l f f -l ff ,.fk'llgfetlresl offthefi-nventinn haxving been: dqseribel and aseertainediwhaais @onsiderea to, be newfanfd 'desired tonliaveprntected-by 30.' Batters@ igntiwilll be-fpointeflivouh im the? I elaine;as'np3@inventionis;j f Y 521., zaxreeefwegyi axhere@#shoes'inaggnet,1 a: diaphragm: af s015713l imm polsi-piacer extending taehedr :toe saidf pole: piece,v saidf. conebeing.;

centrallydoeated ,with respect tosaid da@` phragm; ,ai secondrsoit iron pole-piece? eze--l tending thesecondfffpol off said' perf-r menant fmagnctvdandtermivnmi j in two polar ugsspaced awr-distant" om said core,said second pole piece being formed so thathsaid apolar lags are vconnected 'to the 2'." Ina receiver, a permanent magnet, a.

ydiaphragmwa; softfiron pole piece extending from one pole ofsaid magnet, said pole piece having a -portilonf Whichlieslpwr allel-:..t'o vsaek:diaphragmg aI cone lprleibotil'1g from seid pole: pi'ce ,at night: angles toi .andi centrally :locatedA witlnrespect f toi Smidt diafpflrtgmg mseeond; softpo'le extending! from the' oit-hen pole o'flsaidmagne ande. ternalliatiaig` in: ftwi eqndl shaped Apolini lugs which are parallel to said core,saifl 1 seconds 'pale piece; beingi sof-designedv tha the magnetic; pat-lr :from one; polar:I lug toftfre 1 polecofnthe: magnetg-is-lemtly equalA te* the: magnetic f path! 115mm v the'. othert v polarl lug.. tof saidpole; andi a single-coil elecromagrnet Wonnkirfmwndlid s f l -V 8. A ireceeler ha'vng a; permanent magnet' and' @diaphragm-,7 ai detachable@ sof@ irbn polcrpieee: fon each pole' of the magnet,- one#k f thei other poleifpieee haningrtvro extensions' thefdia? v 

